An integral part of modern medical care is the administration of fluids to a patient through an entry point made in a vein of the patient. A catheter is inserted in the vein and an administration set, comprised principally of flexible tubing, connects the catheter to a source of fluid. Alternatively, medication may be injected into the catheter from a syringe through a drug transfer spike attached to the syringe and a connector having a sealable inlet penetrable by the tip of the drug transfer spike. Y connectors are customarily included in an administration set to allow fluids from two or more sources to flow through a common tube to the patient. Such Y connectors also have a sealable inlet through which the tip of a piercing member can penetrate. The branch containing the sealable inlet in these and other related medical connecting devices is commonly referred to as an "injection site". Injection sites usually feature an elastomeric plug, called a "septum", to form the seal.
One type of injection site includes a slit extending through the septum which permits the injection site to be penetrated by a blunt piercing member. Such pre-slit septums reduce accidental punctures which might result from the use of a sharp-tipped cannula.
One object of the present invention is to minimize leakage through the slit of a pre-slit septum in an injection site during or after being penetrated by a cannula.
When medication is to be administered from a syringe through a drug transfer spike inserted into a connector through its septum, the syringe is first filled from a drug vial through the same drug transfer spike by inserting the spike through the diaphragm that closes the inlet of the drug vial. Since drug vial diaphragms are not pre-slit, the drug transfer spike must be sharp enough to penetrate them. To prevent user injury and contamination, drug transfer spikes should not be sharp enough to easily pierce skin. It is therefore a related object of the invention to provide a drug transfer spike having a piercing member which is sharp enough to penetrate a drug vial diaphragm but blunt enough to prevent coring or abrasion of the septum and also to avoid puncturing a user's skin. An alternative related object of the invention is to provide a syringe with an integral piercing member having the piercing attributes of the aforesaid drug transfer spike.